Hybrid Ensemble-Learning Approach for Renewable Energy Resources Evaluation in Algeria

In order to achieve a highly accurate estimation of solar energy resource potential,a novel hybrid ensemble-learning approach,hybridizing Advanced Squirrel-Search Optimization Algorithm(ASSOA)and support vector regression,is utilized to estimate the hourly tilted solar irradiation for selected arid regions in Algeria.Long-term measured meteorological data,including mean-air temperature,relative humidity,wind speed,alongside global horizontal irradiation and extra-terrestrial horizontal irradiance,were obtained for the two cities of Tamanrasset-and-Adrar for two years.Five computational algorithms were considered and analyzed for the suitability of estimation.Further two new algorithms,namely Average Ensemble and Ensemble using support vector regression were developed using the hybridization approach.The accuracy of the developed models was analyzed in terms of five statistical error metrics,as well as theWilcoxon rank-sum and ANOVA test.Among the previously selected algorithms,K Neighbors Regressor and support vector regression exhibited good performances.However,the newly proposed ensemble algorithms exhibited even better performance.The proposed model showed relative root mean square errors lower than 1.448%and correlation coefficients higher than 0.999.This was further verified by benchmarking the new ensemble against several popular swarm intelligence algorithms.It is concluded that the proposed algorithms are far superior to the commonly adopted ones.

An Overview on Advanced Grid-connected Inverters Used for Decentralized Renewable Energy Resources

并网逆变器是分散式可再生能源接入配电网的重要接口,随着分布式可再生能源渗透率的不断提高,并网逆变器在传统配电网中的地位越发突出。为了高效完成可再生能源分散式并网,并有效降低并网逆变器对电网的冲击,一些在装置上、结构上和功能上更加先进的并网逆变器成为了迫切的需求。针对现有的一些先进并网逆变器进行比较、分析和研究,从装置级、功能级和控制级的角度对现有先进并网逆变器进行综述。给出一些在结构上能更加灵活地将可再生能源分散接入配电网的硬件电路。研究一些适用于可再生能源分散接入的,使并网逆变器能虚拟同步发电机完成自治运行、电能质量治理、系统阻抗检测、网络阻抗控制等辅助控制功能。同时还对并网逆变器的并网同步算法和电流跟踪控制策略进行了探讨。最后,提出一个适合于可再生能源分散并网的先进并网逆变器框架。

Multi-objective planning model for simultaneous reconfiguration of power distribution network and allocation of renewable energy resources and capacitors with considering uncertainties

This research develops a comprehensive method to solve a combinatorial problem consisting of distribution system reconfiguration, capacitor allocation, and renewable energy resources sizing and siting simultaneously and to improve power system's accountability and system performance parameters. Due to finding solution which is closer to realistic characteristics, load forecasting, market price errors and the uncertainties related to the variable output power of wind based DG units are put in consideration. This work employs NSGA-II accompanied by the fuzzy set theory to solve the aforementioned multi-objective problem. The proposed scheme finally leads to a solution with a minimum voltage deviation, a maximum voltage stability, lower amount of pollutant and lower cost. The cost includes the installation costs of new equipment, reconfiguration costs, power loss cost, reliability cost, cost of energy purchased from power market, upgrade costs of lines and operation and maintenance costs of DGs. Therefore, the proposed methodology improves power quality, reliability and security in lower costs besides its preserve, with the operational indices of power distribution networks in acceptable level. To validate the proposed methodology's usefulness, it was applied on the IEEE 33-bus distribution system then the outcomes were compared with initial configuration.

China puts more money in renewable energy resources

In 2010, over 300 billion yuan ($47.31 billion) are invested in renewable energy sources in China, outranking every other country. Hence, China has become one of the world’s biggest investors in renewable energy sources.

Tapping Renewable Energy Resources -with A Combined Capacity of 1236 MW as Target for the Year 2000

China began the research and development of renewable energy generation since 1970s, in particular in the Eighth Five-year Plan period, the State made closer attention to the research and development of renewable energy, therefore the technical level, application scale and economic, social benefits have seen greater progress. The combined capacity of renewable energy generation reached 100 MW at the end of 1994. And it is planned a combined capacity of 1236 MW will be targeted for the year 2000.

Intelligent Fractional-Order Controller for SMES Systems in Renewable Energy-Based Microgrid

An autonomous microgrid that runs on renewable energy sources is presented in this article.It has a supercon-ducting magnetic energy storage(SMES)device,wind energy-producing devices,and an energy storage battery.However,because such microgrids are nonlinear and the energy they create varies with time,controlling and managing the energy inside them is a difficult issue.Fractional-order proportional integral(FOPI)controller is recommended for the current research to enhance a standalone microgrid’s energy management and performance.The suggested dedicated control for the SMES comprises two loops:the outer loop,which uses the FOPI to regulate the DC-link voltage,and the inner loop,responsible for regulating the SMES current,is constructed using the intelligent FOPI(iFOPI).The FOPI+iFOPI parameters are best developed using the dandelion optimizer(DO)approach to achieve the optimum performance.The suggested FOPI+iFOPI controller’s performance is contrasted with a conventional PI controller for variations in wind speed and microgrid load.The optimal FOPI+iFOPI controller manages the voltage and frequency of the load.The behavior of the microgrid as a reaction to step changes in load and wind speed was measured using the proposed controller.MATLAB simulations were used to evaluate the recommended system’s performance.The results of the simulations showed that throughout all interruptions,the recommended microgrid provided the load with AC power with a constant amplitude and frequency.In addition,the required load demand was accurately reduced.Furthermore,the microgrid functioned incredibly well despite SMES and varying wind speeds.Results obtained under identical conditions were compared with and without the best FOPI+iFOPI controller.When utilizing the optimal FOPI+iFOPI controller with SMES,it was found that the microgrid performed better than the microgrid without SMES.

Low-carbon generation expansion planning considering uncertainty of renewable energy at multi-time scales

With the development of carbon electricity,achieving a low-carbon economy has become a prevailing and inevitable trend.Improving low-carbon expansion generation planning is critical for carbon emission mitigation and a lowcarbon economy.In this paper,a two-layer low-carbon expansion generation planning approach considering the uncertainty of renewable energy at multiple time scales is proposed.First,renewable energy sequences considering the uncertainty in multiple time scales are generated based on the Copula function and the probability distribution of renewable energy.Second,a two-layer generation planning model considering carbon trading and carbon capture technology is established.Specifically,the upper layer model optimizes the investment decision considering the uncertainty at a monthly scale,and the lower layer one optimizes the scheduling considering the peak shaving at an hourly scale and the flexibility at a 15-minute scale.Finally,the results of different influence factors on low-carbon generation expansion planning are compared in a provincial power grid,which demonstrate the effectiveness of the proposed model.

Strategic Renewable Energy Resource Selection Using a Fuzzy Decision-Making Method

Renewable energy is created by renewable natural resources such as geothermal heat,sunlight,tides,rain,and wind.Energy resources are vital for all countries in terms of their economies and politics.As a result,selecting the optimal option for any country is critical in terms of energy investments.Every country is nowadays planning to increase the share of renewable energy in their universal energy sources as a result of global warming.In the present work,the authors suggest fuzzy multi-characteristic decision-making approaches for renew-able energy source selection,and fuzzy set theory is a valuable methodology for dealing with uncertainty in the presence of incomplete or ambiguous data.This study employed a hybrid method for order of preference by resemblance to an ideal solution based on fuzzy analytical network process-technique,which agrees with professional assessment scores to be linguistic phrases,fuzzy numbers,or crisp numbers.The hybrid methodology is based on fuzzy set ideologies,which calculate alternatives in accordance with professional functional requirements using objective or subjective characteristics.The best-suited renewable energy alternative is discovered using the approach presented.

Study of the development road map of China’s renewable energy

Renewable energy (RE) has been attached high attention around the world due to its carbon-free and indigenous production in a sustainable way. China enjoys plenty of renewable energy resources, particularly the wind, solar, hydro- and biomass energy, which could be a sound basis for a large-scale exploitation. This report examines the current status of RE technology and industry, analyzes the challenges of promoting RE in China. In order to pave the way for a long-term development of RE, this paper outlines the basic principles and priorities for individual RE technology. In line with these, the paper puts forward the RE targets and further describes the RE road map by 2020, 2030 and extend to 2050, taking consideration of China’s RE resources, industrial basis and energy demand etc. At last, this paper provides some recommendations to ensure the achievements of the RE targets.

Status of Renewable Energy Applications in the Malaysian Energy Mix

Demand for power in Malaysia is projected to double the current demand in 2030. The current fuel mix for power generation is heavily dependent on fossil fuels. This has created energy supply and environmental sustainability concerns to the industry. Furthermore, at the recent United Nations Climate Change Conference 2009-15th Conference of Parties （COP15）, Malaysia had given the commitment to voluntary reduction of up to 40% in terms of emissions intensity of GDP by the year 2020 compared to 2005 levels. Renewable energy （RE） provides the best alternative in addressing these issues. In 2001, RE was regarded as the fifth fuel in the new Five Fuel Strategy of the National Energy Policy. Small Renewable Energy Program （SREP） was launched with the main objective of supporting the government＇s strategy to intensify the development of RE as the fifth fuel resource. Biomass, the largest amongst the main RE resources available, can be used for heat and power generation. With optimum utilization, the value ofbiomass resources in Malaysia is estimated to be more than RM 500 billion （USD 156 billion） over the next 20 years. Malaysia has the capacity to use renewable energy resources to address the national energy agenda.

Evaluation and re-understanding of the global natural gas hydrate resources

Natural gas hydrate(NGH)has been widely considered as an alternative to conventional oil and gas resources in the future energy resource supply since Trofimuk’s first resource assessment in 1973.At least 29 global estimates have been published from various studies so far,among which 24 estimates are greater than the total conventional gas resources.If drawn in chronological order,the 29 historical resource estimates show a clear downward trend,reflecting the changes in our perception with respect to its resource potential with increasing our knowledge on the NGH with time.A time series of the 29 estimates was used to establish a statistical model for predict the future trend.The model produces an expected resource value of 41.46×1012 m3 at the year of 2050.The statistical trend projected future gas hydrate resource is only about 10%of total natural gas resource in conventional reservoir,consistent with estimates of global technically recoverable resources(TRR)in gas hydrate from Monte Carlo technique based on volumetric and material balance approaches.Considering the technical challenges and high cost in commercial production and the lack of competitive advantages compared with rapid growing unconventional and renewable resources,only those on the very top of the gas hydrate resource pyramid will be added to future energy supply.It is unlikely that the NGH will be the major energy source in the future.

Plasma-electrified up-carbonization for low-carbon clean energy

Low-value,renewable,carbon-rich resources,with different biomass feedstocks and their derivatives as typical examples,represent virtually inexhaustive carbon sources and carbon-related energy on Earth.Upon conversion to higher-value forms(referred to as“up-carbonization”here),these abundant feedstocks provide viable opportunities for energy-rich fuels and sustainable platform chemicals production.However,many of the current methods for such up-carbonization still lack sufficient energy,cost,and material efficiency,which affect their economics and carbon-emissions footprint.With external electricity precisely delivered,discharge plasmas enable many stubborn reactions to occur under mild conditions,by creating locally intensified and highly reactive environments.This technology emerges as a novel,versatile technology platform for integrated or stand-alone conversion of carbon-rich resources.The plasma-based processes are compatible for integration with increasingly abundant and cost-effective renewable electricity,making the whole conversion carbon-neutral and further paving the plasma-electrified upcarbonization to be performance-,environment-,and economics-viable.Despite the chief interest in this emerging area,no review article brings together the state-of-the-art results from diverse disciplines and underlies basic mechanisms and chemistry underpinned.As such,this review aims to fill this gap and provide basic guidelines for future research and transformation,by providing an overview of the application of plasma techniques for carbon-rich resource conversion,with particular focus on the perspective of discharge plasmas,the fundamentals of why plasmas are particularly suited for upcarbonization,and featured examples of plasma-enabled resource valorization.With parallels drawn and specificity highlighted,we also discuss the technique shortcomings,current challenges,and research needs for future work.

An Analysis of Renewable Water Sources in Saudi Arabia

Kingdom of Saudi Arabia (KSA) is located in a very harsh natural desert environment with no rivers or lakes and an average yearly rainfall of less than 100 mm. The country is under extreme water shortage conditions. KSA utilizes conventional (natural) and unconventional water resources to satisfy the ever increasing water demand. The purpose of this paper is to analyze two approaches to obtaining fresh water from renewable water resources, namely they are seawater distillation using solar energy and gathering liquid water from fog. In order to conduct the study for seawater distillation a solar still basin has been designed, manufactured and tested in selected day for saline water in month of April, 2012. The solar still consists of insulated metal box with channels. Pyramidal glass covers attached to the basin at an angle (=45°), and the basin area of the still is 0.25 m2 and filled with 6 liters of seawater. The average daily output was found to be 3.924 liters/day. Further, to harvesting water from fog a Standard Fog Collector (SFC) was designed and manufactured in Asir region with locally available materials and imported mesh. This SFC was installed in April 2012. The site was chosen based on topography and altitude and data from April 2012 to March 2013 were obtained. Measurements with the SFC were made for region with 3200 m elevation. The results indicate that the average water production was 6.225 L/(m2·day) over the studied period and the highest average water production was recorded in December 11.20 L/(m2·day). The highest water collection was 20 L/(m2·day) and recorded in Jan. 05, 2013 at Rayda site, and furthermore for the same site, the best average water production of 10.52 L/(m2·day) was obtained in winter three months period namely (December, November and January).

Demand Responsive Market Decision-Makings and Electricity Pricing Scheme Design in Low-Carbon Energy System Environment

The two-way interaction between smart grid and customers will continuously play an important role in enhan-cing the overall efficiency of the green and low-carbon electric power industry and properly accommodating intermittent renewable energy resources.Thus far,the existing electricity pricing mechanisms hardly match the technical properties of smart grid;neither can they facilitate increasing end users participating in the electri-city market.In this paper,several relevant models and novel methods are proposed for pricing scheme design as well as to achieve optimal decision-makings for market participants,in which the mechanisms behind are com-patible with demand response operation of end users in the smart grid.The electric vehicles and prosumers are jointly considered by complying with the technical constraints and intrinsic economic interests.Based on the demand response of controllable loads,the real-time pricing,rewarding pricing and insurance pricing methods are proposed for the retailers and their bidding decisions for the wholesale market are also presented to increase the penetration level of renewable energy.The proposed demand response oriented electricity pricing scheme can provide some useful operational references on the cooperative operation of controllable loads and renewable energy through the feasible retail and wholesale market pricing methods,and thereby enhancing the development of the low-carbon energy system.

Bioeconomy in the Agrarian Resources Potential System of Ukraine

The main goal of this research is to determine the importance and prospects of bioeconomy development in agriculture of Ukraine for international economic integration.Actual reason for this research is military occupation of west regions and the macroeconomic instability.Available resources form supply potential for agrarian production,renewable energy,and sustainable development.However,unemployment of labour,land,and capital determine the inflationary gap,which could be closed in two main ways:The innovative economic growth in business and households’sectors in accordance to bio-based principles and rational government state regulation with fiscal and monetary policies instruments.The external and internal effects of bioeconomy development in the agrarian resources system are determined in accordance to strengths,weaknesses,opportunities,and threats(SWOT)-analysis.European integration requires entrepreneurial initiative,environmental protection,social benefits in the satisfaction of individual needs of the population,modern principles of competition,such as mutual beneficial cooperation and new market creation for food security and human resources development.

Communication Resources Allocation for Time Delay Reduction of Frequency Regulation Service in High Renewable Penetrated Power System

The high renewable penetrated power system has severe frequency regulation problems.Distributed resources can provide frequency regulation services but are limited by com-munication time delay.This paper proposes a communication resources allocation model to reduce communication time delay in frequency regulation service.Communication device resources and wireless spectrum resources are allocated to distributed resources when they participate in frequency regulation.We reveal impact of communication resources allocation on time delay reduction and frequency regulation performance.Besides,we study communication resources allocation solution in high renewable energy penetrated power systems.We provide a case study based on the HRP-38 system.Results show communication time delay decreases distributed resources'ability to provide frequency regulation service.On the other hand,allocating more communication resources to distributed resources'communica-tion services improves their frequency regulation performance.For power systems with renewable energy penetration above 70%,required communications resources are about five times as many as 30%renewable energy penetrated power systems to keep frequency performance the same.Index Terms-Communication resources allocation,commun-ication time delay,distributed resource,frequency regulation,high renewable energy penetrated power system.

Apply of Low-Carbon Technology in Building Energy Conservation in Hot Summer and Cold Winter Area

Building energy conservation is the basis for carbon emission reduction, through elaborating the relationship between low carbon and energy efficient building. It points out that the construction of energy-saving emission reduction is an effective means to solve the problems of high energy consumption of the building, and it is also an important measure for China＇s carbon emission reduction. According to the climate characteristics in hot summer and cold winter area, low carbon technology suitable for the construction of energy-efficient hot summer and cold winter area is proposed which is based on the analysis of the current main building energy-saving technical measures.

Energy Economic Dispatch for Photovoltaic-Storage via Distributed Event-Triggered Surplus Algorithm

This paper presents a novel approach to economic dispatch in smart grids equipped with diverse energy devices.This method integrates features including photovoltaic(PV)systems,energy storage coupling,varied energy roles,and energy supply and demand dynamics.The systemmodel is developed by considering energy devices as versatile units capable of fulfilling various functionalities and playing multiple roles simultaneously.To strike a balance between optimality and feasibility,renewable energy resources are modeled with considerations for forecasting errors,Gaussian distribution,and penalty factors.Furthermore,this study introduces a distributed event-triggered surplus algorithm designed to address the economic dispatch problem by minimizing production costs.Rooted in surplus theory and finite time projection,the algorithm effectively rectifies network imbalances caused by directed graphs and addresses local inequality constraints.The algorithm greatly reduces the communication burden through event triggering mechanism.Finally,both theoretical proofs and numerical simulations verify the convergence and event-triggered nature of the algorithm.

Optimal Operation of an Integrated Electricity-heat Energy System Considering Flexible Resources Dispatch for Renewable Integration

Large fluctuations may occur on the energy supply and the load sides when large-scale renewable energies are integrated,leading to great challenges in power systems.The renewable power curtailment is especially numerous in the integrated electricity-heat energy system(IEHES)on account of electricity-heat coupling.The flexible resources(FRs)on both the energy supply and load sides are introduced into the optimal dispatch of the IEHES and further modeled to alleviate the renewable fluctuations in this paper.On the energy supply side,three kinds of FRs based on electricity-heat coordination are modeled and discussed.On the load side,the shiftable electricity demand resource is characterized.On this basis,the solution for FRs participating in IEHES dispatch is given,with goals of maximizing the renewable penetration ratio and lowering operation costs.Two scenarios are performed,and the results indicate that the proposed optimal dispatch strategy can effectively reduce the renewable energy curtailment and improve the flexibility of the IEHES.The contribution degrees of different FRs for renewable integration are also explored.

Stochastic Security-constrained Unit Commitment Considering Electric Vehicles, Energy Storage Systems, and Flexible Loads with Renewable Energy Resources

In this paper, a new formulation for modeling the problem of stochastic security-constrained unit commitment along with optimal charging and discharging of large-scale electric vehicles, energy storage systems, and flexible loads with renewable energy resources is presented. The uncertainty of renewable energy resources is considered as a scenario-based model. In this paper, a multi-objective function which considers the reduction of operation cost, no-load and startup/shutdown costs, unserved load cost, load shifting, carbon emission, optimal charging and discharging of energy storage systems, and power curtailment of renewable energy resources is considered. The proposed formulation is a mixed-integer linear programming(MILP) model, of which the optimal global solution is guaranteed by commercial solvers. To validate the proposed formulation, several cases and networks are considered for analysis, and the results demonstrate the efficiency.